Hi vipulgoyal,
This SC comes down to Pronoun rules.
1) Pronouns (Singular vs. Plural): The prompt refers to "a child", which is a singular noun. The correct pronoun would have to be either "he" or "she", not "their." Eliminate A, B and D.
2) Relative Pronoun/Usage: Between C and E, there's an interesting issue - whether we need the relative pronoun "which" or not. Since the prompt specifically refers to two nouns "wealth" and "position", the relative pronoun "which" is fine AND the verb "are" is correct, so I would side with Answer C. There might be some rare idiom/usage rule about the phrase "natural birthright", that would make those words unnecessary, but I can't think of one.
Final Answer: C
GMAT assassins aren't born, they're made,
Rich